02

GEOSPATIAL SERVICES FOR DECISION SUPPORT ON PUBLIC HEALTH
S. Gao a, *, D. Mioc a, X. Yi b, F. Anton c, E. Oldfield b
a
Department of Geodesy and Geomatics Engineering, University of New Brunswick, Canada - (sheng.gao,
dmioc)@unb.ca
b
New Brunswick Lung Association, Canada – xiaolun.yi@gmail.com, eddie.oldfield@nb.lung.ca
c
Department of Informatics and Mathematical Modeling, Technical University of Denmark, Denmark –
fa@imm.dtu.dk
KEY WORDS: GIS, Internet/Web, Mapping, Interoperability, Decision Support, Public Health
ABSTRACT:
Sharing of health information is critical for preventing disease, responding to emergencies, educating the public and policy makers.
Protecting privacy and confidentiality of health information remain important cornerstones of the public health system, however
many health professionals and authorities do not have the ability to visualize health information to make time-sensitive decisions,
since they do not have the time, money, or skills to statistically analyze vast amounts of distributed data and render aggregated
results into a geographic interface for quick interpretation. The technology to do so, web based geographic information systems and
related standards, has matured yet confidence in such technology to visualize or share health information is only beginning to
emerge. Currently, four major problems still exist in health geographic applications. They are related to health mapping methods,
mapping variables, reusability of health applications, and interoperability issues. To handle these problems, we designed a Health
Representation XML schema and SOA based architecture to support health data sharing and representation. The schema makes it
possible to exchange the statistical results of health data as well as representation through XML and GML. The OGC services such
as WMS, WFS, and WPS enable the statistical exploration and representation of health information. A Web-portal is developed to
support the integration of different services for visualization of health maps, hypothesis generation, and decision making. This
architecture provides quick access to spatial and health data for understanding the trends in diseases, and promotes the growth and
enrichment of the SDI in the public health sector.
1. INTRODUCTION integrating and editing many kinds of data that are located on
the Earth’s surface, such as health, social, environment data.
Currently, many determinants such as booming population, Visualization and mapping can explore the spatial patterns and
environmental pollution, rapid urbanization, convenient correlations of diseases and many factors such as census and
transportation, and global warming are improving the environment. Spatial analysis utilizes the spatial relationship to
conditions for disease outbreaks. To prevent and mitigate the generate new health patterns. For instance, Kriging is a popular
risk of diseases, it is important to build a robust health system method used for interoperating health data. When a disease
to support evidence based decision making. The sharing of appears, GIS can represent disease information rapidly and
essential health information is one of the most feasible routes to analyze the spread of disease dynamically.
achieve global public security (WHO, 2007). There is strong
need for access to maps on disease prevalence, mortalities, Meanwhile, the rapid development of the Internet promotes the
health determinants, transmission patterns, and components of popularity of Web-based GIS, which itself shows great potential
healthcare responses. for the sharing of health information through distributed
networks. Distributing and sharing health maps via the Web
As health phenomena have revealed strong spatial aspects, helps decision makers across health jurisdictions and authorities
maps can show geographic distributions and spatial patterns of collaborate in preventing, controlling, and responding to a
diseases. Analyzing and mapping the spatial aspects of disease specific disease outbreak. Users without tools or without
can improve our understanding of disease etiology, facilitate necessary skills can make use of GIS functions through Web-
work with therapists to educate the public, and augment based GIS (Wright et al., 2003). The Documented applications
decision-making on programs that aim to prevent illnesses. The are already making health information accessible through the
health applications using spatial components of diseases can be Web (Benneyan et al., 2000; Edberg, 2005). Custom online
traced back to 1854 when Dr. John Snow combined geospatial interactive health maps can be implemented using Google Maps
information to analyze the cholera deaths and found clusters API, Google Earth KML or MSN Virtual Earth Map Control
around water pumps (McLeod, 2000). There are three important (Boulos, 2005). Several Web-based GIS applications can
functions of Geographical Information System (GIS) in health generate disease maps dynamically from the server side
research and policy analysis: spatial database management, (Blanton et al. 2006;Inoue et al. 2003), while other applications
visualization and mapping, and spatial analysis (Cromley and employ Java Applets and Scalable Vector Graphics (SVG)
McLafferty, 2002). Database management include linking, approaches to visualize health information (Kamadjeu and
Tolentino, 2006; Qian et al., 2004). Boulos and Honda (2006)
* Corresponding author.
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proposed to publish health maps through Web Map Service spatial, temporal, and demographic factors and their influence
with Open Source Web-based GIS software. on health related activities, which can show the health
information distribution with spatial, temporal, age, and gender
differences. Other statistical methods can be introduced to
2. EXISTING PROBLEMS ON HEALTH GEOGRAPHIC support more influential factors.
APPLICATIONS
XML is very popular in supporting the data exchange in
In spite of the continuous development of geographical health heterogeneous systems. Health Level 7 (HL7) standards that are
applications, the following four problems still need to be accredited by non-profit America National Standards Institute,
handled. allow representation and exchange of information from online
patient records to pharmacy formularies in HL7 XML
Firstly, the methods to generate maps from health related documents. The primary domain of HL7 standards is clinical
activities need to be considered. There are different kinds of and administrative data, and explicit spatial information and
health activities, such as hospital observation, laboratory tests health data mapping are not considered. Instead of exchanging
and results, healthcare and medication services, and training huge raw clinical data for health mapping, we focus on creating
and education for patients. Since these activities are social a Health Representation XML (HRXML) schema for the
events and related to spatial location, a proper way to support sharing of the statistical results of health data as well as their
mapping of these activities on maps is a foremost concern in representation. In the design process, our intention is to make
health geographic applications. Many web-based health the schema as simple and extendable as possible. Three
applications dynamically generate maps, but they lack data dimensions of representation are related with spatial data:
source description, and method declaration on how the maps are semantic, geometric and graphical (Bédard and Bernier, 2002).
generated. Therefore, we include these three kinds of representations in the
HRXML schema. Semantic representation describes the health
Secondly, many mapping dimensions for health data related activities and the statistical methods used. Geometric
representation should be supported. In finding support of dimension shows what type of geometry (point, line, and
disease surveillance, the variables in disease type dimension, polygon) will be used to represent these health data. Graphic
temporal dimension, gender dimension, and age dimension are representation defines what styles or symbols are used to
valuable. For instance, disease patterns show striking generate health maps.
differences at different representation scales, which is
recognized in many health studies (Albert et al., 2000; Leitner As shown in Figure 1, the designed HRXML schema includes
and Curtis, 2006). three parts: health, mapping data, and representation.
Thirdly, integrating and reusing current health applications are
constrained to a large extent. Zeng et al. [15] pointed out that
the isolation of existing stand-alone disease management
systems leads to a data sharing problem. Most of the health
information systems have a closed architecture - even the ones
that use web-based technology are difficult to integrate.
Typically, users can only access maps from such a health
application, and it is difficult to integrate datasets from these
applications.
Fourthly, different health application lacks interoperability
between them. Interoperability makes it easy to communicate,
execute programs, or transfer data among various systems in a
unified manner. With closed and centralized legacy architecture,
a web-based GIS system can not fully adapt to current
distributed, heterogeneous network environments, and is
unlikely to provide users with the needed data and services due
to its lack of interoperability, modularity, and flexibility (He et
al., 2005). In health decision making, it is important to access
various kinds of data such as hospital locations and available
medical resources through standard interfaces.
3. HRXML FOR HEALTH REPRESENTATION DATA Figure 1. HRXML schema
EXCHANGE
The health part includes the basic information of the health
In the mapping of health related activities, statistical methods
related activities, with the name, title, description, and
are used to connect health related activities with maps. The
keywordList elements, and a type attribute. HealthType is an
following statistical methods are considered in this research:
abstract complex type. It can be extended to support disease
Crude Morbidity Rate (CMR), Normalized Morbidity Ratio
observation or other activities.
(NMR), Age-Specific Morbidity Ratio (ASMR), Age-Adjusted
Morbidity Ratio (AAMR), and Standardized Morbidity Ratio
The mapping data part mainly records the data used for
(SMR), Summation, Mean, Standard Deviation, Variance,
mapping. As shown in Figure 2, it includes the bounding box of
Skewness and Kurtosis. These methods are concentrated on
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the data, spatial data, relation between spatial data and mapping styles, the health data can be shown as thematic maps, which
values, and mapping values. make information communication more understandable.
--“BoundingBox” represents the spatial range of the mapping 4. ARCHITECTURE DESIGN FOR HEALTH
data. APPLICATIONS
--“SpatialData” could be GML from WFS services, GML Service oriented architecture provides a flexible way to share
records, or Xlink to GML databases. The health data are data as well as processing functions over the Internet to reduce
statistical values and are linked with the spatial data through the costs of building complex systems. The service oriented
joining attribute. architecture supports loose coupling between components and
makes services reusable. As a result, Spatial Data Infrastructure
-- “Relation” records the joining attribute and the matching ID (SDI) has been evolving from data driven architecture to service
value of both spatial data and mapping values. oriented architecture. To address geospatial data sharing and
interoperability, Open Geospatial consortium (OGC) has been
--“Mapping values” includes the health data source description, developing several specifications, such as Web Map Service
statistical method used and mapping value lists. The statistical (WMS), Web Feature Service (WFS), and Web Processing
method part describes the name, title, description, health data Service (WPS). WMS publishes its ability to produce maps
source, and statistical parameters of the statistical method used. rather than its ability to access specific data holdings, and
Statistical methods are used to generate classification maps and generates spatially referenced maps dynamically (OGC, 2001).
charts for health related activities. We predefined some WFS defines the interfaces for the access and manipulation of
parameters from the spatial, temporal, and demographic aspects geographical features and elements through Geography Markup
for public health, such as AgeFrom, AgeTo, and StartTime, Language (GML) (OGC, 2005b). WPS provides standardized
which can show health distributions with spatial, temporal, age interfaces to facilitate publishing, discovery and binding
and gender differences. Users can add additional parameters in geospatial services that enable spatial processing functions
the parameter group to support advanced statistical methods. across a network (OGC, 2005a).
Accessing health information through standard interfaces is
important to achieve interoperability. In this way, such access
could improve the ability to intervene in health issues, and
inform the public of the availability of resources and
community health programs. To accomplish a web-based
application for statistical exploration of health information, we
take advantage of the standard OGC services including WMS,
WFS, and WPS. The proposed architecture (see Figure 3)
includes three tiers: a data tier, a service tier and a web portal
tier.
Figure 2. The mapping data part schema
The Representation part defines the kind of style used to
represent health maps. It consists of the default representation
bounding box and style description. Depending on the kind of Figure 3. System architecture
representation, the StyleType is further extended to
ChartStyleType, PointStyleType, LineStyleType, and The data tier stores all the health related data and spatial data
PolygonStyleType. For instance, the PolygonStyleType for health studies. These data could be available from databases
includes the border and fill elements. The type of filling in a or web services.
polygon can be gradient fill or range based fill. For the range
based fill, the fill method can use colour, pattern, and texture. The service tier implements WMS, WFS, and WPS for health
The border element contains the colour, line style and line studies.
weight of the border.
--WMS provides standard interfaces to generate maps and
In the HRXML, the spatial related statistical health data are charts for visualization of health information. It utilizes the
well described and able to be exchanged. With representation health mapping module to generate maps. The health module
can generate various style maps such as unique colour
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classification, graduate colour classification, pie charts and bar A portal has been implemented in the integration of these OGC
charts, to show events or facilities distribution. The input data services for decision making. The public HTML portal provides
could be obtained from HRXML, GML, WFS, WPS, Oracle access to aggregate health maps for the general public. The
DBMS, Key-Value documents, or shape files. HTML portal is developed to allow easy and quick access to
WMS/WPS services for visualization purposes. As shown in
--WFS uses the GML transformation module to share spatial Figure 5, a CMR distribution map from WPS and some facility
data through GML. It can be linked with the mapping values distribution maps from WMS are integrated. It provides users
(part of HRXML) to create thematic health maps. (researchers, health officials, practitioners, policy makers, and
epidemiologists) with access to GIS functionality for
--WPS is used to analyze spatial-temporal health data. The visualizing health data, and evidence-based decision-making on
health data analysis supports data rolling up from a low spatial disease outbreaks.
level to a high spatial level. WPS uses the health mapping
module and statistical procedure module to calculate the result,
and the output could be HRXML or health maps (JPEG, PNG,
GIF, and GeoTIFF). The input data of WPS could be obtained
from WFS, GML Oracle DBMS, or shape files.
The web portal tier is a client for the visualization of disease
data and maps. It can bring together different facets of health
information into one location to improve health promotion and
health care research, education, and policy-making.
5. IMPLEMENTATION
Based on the above framework, we implement a prototype for
the sharing of health information. The health data we used
include four kinds of respiratory disease data collected by the
New Brunswick Lung Association. The disease data are geo-
coded to spatial position through the postcode. The spatial data Figure 5. The web portal interface
we used include the six levels of spatial boundary data that
cover the entire territory of New Brunswick. The six levels are
"Province", "Health Region", "Census Division", "Census 6. CONCLUSION
Subdivision", "Forward Sortation Area", and "Dissemination
In this research, we have applied the service oriented
Area" geo-layers. All the health data and geometrical boundary
architecture in health geographic applications, with many
data are stored in Oracle 11g. With the spatial operation
standard WMS, WFS, and WPS services. This architecture will
provided by Oracle, the disease data can be easily rolled up
facilitate the data sharing as well as the reusability and
from a low spatial level to a high level, and low counts i.e. less
interoperability of health services. We develop the HRXML
than five observations, or false counts are not represented to
schema to exchange statistical health data as well their
further ensure privacy and accuracy. We use CARIS WMS and
representation based on XML and GML specifications. A user-
WFS to publish the data. The implementation of health
friendly web application has been built for the exploratory and
mapping module utilizes the Geotools library. The statistical
descriptive analysis of health information, hypothesis-
procedure model is implemented with the Oracle PL/SQL code.
generation, and decision-making. It provides quicker access to
The client side is developed using Javascript and HTML.
spatial and health data in understanding the trends in disease,
and promotes the growth and enrichment of the SDI in the
Figure 4 shows an example of an HRXML document generated
public health sector. Sharing of health information can improve
by WPS.
the ability to intervene in health issues, and inform the public of
the availability of resources, reduce the number of people
affected by illness, and therefore reduce costs to the health-care
system. Our future work will be on the implementation of the
OGC Web Catalogue Service and accomplish the semantic
query and access of health geographic services.
ACKNOWLEDGMENTS
This research work has received the financial support from
GeoConnections secretariat of natural resources Canada for a
project titled “Development of Web Application and Services
within the CGDI framework for Community Health Programs
of the New Brunswick Lung Association”.
Figure 4. An HRXML example
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